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SubjectRe: [PATCH v2] net: netfilter: Fix ipv6 rp_filter dropping vrf packets by mistake
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On 4/24/19 3:12 AM, linmiaohe wrote:
> From: Miaohe Lin <linmiaohe@huawei.com>
>
> When firewall is enabled with rp_filter, vrf ipv6 packets
> will be dropped because in device is vrf but out device
> is an enslaved device. So rt->rt6i_idev->dev != dev and
> maybe return false in func rpfilter_lookup_reverse6.
>
> Here is the out message when I ping the peer:
> ip vrf exec vrf1 ping 2013::2 -c 1
> 1 packets transmitted, 0 received, 100% packet loss, time 0ms
>
> The drop info in /var/log/message:
> Apr 24 14:59:45 localhost kernel: [81316.158259] rpfilter_DROP: IN=vrf1
> OUT= MAC=52:54:00:9e:dd:c1:52:54:00:4f:81:38:86:dd
> SRC=2013:0000:0000:0000:0000:0000:0000:0002
> DST=2013:0000:0000:0000:0000:0000:0000:0001 LEN=104 TC=0 HOPLIMIT=64
> FLOWLBL=1032942 PROTO=ICMPv6 TYPE=129 CODE=0 ID=14943 SEQ=1
>
> Signed-off-by: linmiaohe <linmiaohe@huawei.com>
> ---
> net/ipv6/netfilter/ip6t_rpfilter.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c b/net/ipv6/netfilter/ip6t_rpfilter.c
> index c3c6b09acdc4..cf1070ab1252 100644
> --- a/net/ipv6/netfilter/ip6t_rpfilter.c
> +++ b/net/ipv6/netfilter/ip6t_rpfilter.c
> @@ -73,6 +73,12 @@ static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
> goto out;
> }
>
> + if (netif_is_l3_master(dev)) {
> + dev = dev_get_by_index_rcu(dev_net(dev), IP6CB(skb)->iif);
> + if (!dev)
> + goto out;
> + }
> +
> if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE))
> ret = true;
> out:
>

What about the case where XT_RPFILTER_LOOSE is set? flowi6_oif needs to
be set to the dev->ifindex if dev is an l3 master.

And looking at the IPv4 version I do not see how it could be correct
either. Have you tested it?

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